Cooled containment compartments for packaged battery cells

ABSTRACT

An air plenum assembly includes a first plenum for cooling, where the first plenum includes an inlet for air intake located at a first side of the first plenum. The air plenum assembly further includes a second plenum for exhausting heated air, where the second plenum includes an outlet for exhausting air located at a first side of the second plenum. The air plenum assembly further includes a first aperture located on a first side of the first plenum for directing air from the inlet at the first side of the first plenum to a first compartment and includes a first vent located on a first side of the second plenum for exhausting air away from the first compartment towards the outlet at the first side of the second plenum. The first compartment is isolated from surrounding battery compartments by at least two thermal separators.

FIELD OF THE INVENTION

This disclosure relates generally to packaged battery cells, and inparticular, to structures for cooling and containing individual packagedbattery cells.

BACKGROUND OF THE INVENTION

Over time, energy density in batteries has increased, while packagingsize for the batteries has decreased. Lithium ion batteries are anexample of high energy density batteries and have become the preferredbattery technology for items such as, consumer electronics, electricvehicles, battery backup systems, and other energetic systems requiringa mobile and rechargeable power source. A byproduct of high energydensity is that lithium ion batteries pose a greater safety risk thanlower energy density technologies, due to the amount of chemical energystored in a small package. A mechanism by which high energy densitybatteries fail energetically is called thermal runaway, a conditionwhere the chemical reaction inside a single cell becomes unstable due toexcessive heat which may be generated by an internal defect or by othermeans. Thermal runaway causes the single cell to continue to heat up atan ever-accelerating rate until the structural integrity of the singlecell is compromised or the single cell combusts.

SUMMARY

One aspect of an embodiment of the present invention discloses anapparatus for an air plenum assembly comprising a first plenum enclosedby a first conduit for cooling, wherein the first plenum includes aninlet for air intake located at a first side of the first plenum; asecond plenum enclosed by a second conduit for exhausting heated air,wherein the second plenum includes an outlet for exhausting air locatedat a first side of the second plenum, wherein a second side of the firstplenum is at least partially coupled lengthwise to a second side of thesecond plenum; a first aperture located on a third side of the firstplenum for directing air from the inlet at the first side of the firstplenum to a first compartment, wherein the first compartment includes afirst battery cell; and a first vent located on a third side of thesecond plenum for exhausting air away from the first compartment towardsthe outlet at the first side of the second plenum.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the disclosure solely thereto, will best beappreciated in conjunction with the accompanying drawings, in which:

FIG. 1A depicts an air plenum assembly, in accordance with an embodimentof the present invention.

FIG. 1B depicts an enhanced view of a portion of the air plenum assemblyof FIG. 1A, in accordance with an embodiment of the present invention.

FIG. 2 depicts an isometric view of a plurality of air plenum assembliesin a battery cell package, in accordance with one embodiment of thepresent invention.

FIG. 3 depicts a top view of the plurality of air plenum assemblies inthe battery cell package of FIG. 2, in accordance with one embodiment ofthe present invention.

FIG. 4 depicts an enhanced top view of a single row of battery cellswith an air plenum assembly in the battery cell package of FIG. 2, inaccordance with one embodiment of the present invention.

FIG. 5 depicts a front inlet view of the plurality of air plenumassemblies in the battery cell package of FIG. 2, in accordance with oneembodiment of the present invention.

FIG. 6 depicts a rear outlet view of the plurality of air plenumassemblies in the battery cell package of FIG. 2, in accordance with oneembodiment of the present invention.

DETAILED DESCRIPTION

The cooling of battery cells prevents battery cell overheating duringcharging and discharging which can lead to thermal runaway.Additionally, the cooling of battery cells removes excess heat duringcertain events, such as small internal shorts, which may not result inthermal runaway. The containment of battery cells prevents anuncontrolled event (e.g., fire) from exiting the battery cell packageand causing damage or injury. The containment of a single battery cellprevents a single battery cell thermal runaway event from propagating tosurrounding battery cells and creating a thermal runaway event acrossall the battery cells within the battery cell package.

Smaller battery cell packages, such as those found in smart phones, aretypically cooled using conduction and natural convection. These batterycell packages may also utilize a containment unit which encases thebattery cells, where the containment unit is tight against the cells andis thermally coupled to the battery cells. The containment units preventdamage due to an uncontrolled event or thermal runaway, and also assistwith the cooling via conduction and natural convection.

However, conduction and natural convention may not provide enoughcooling to larger battery cell packages. Larger battery cell packagesare typically cooled utilizing a liquid coolant, where the coolant flowsthrough tubing and piping around the battery cells to cool the batterycell package. The coolant draws heat away from the battery cells andallows for a containment unit to be placed around the cells to prevent athermal runaway event from escaping the confines of the battery cellpackage. Some larger battery cell packages separate the battery cellsinto smaller clusters or modules which are isolated, preventing acascading failure of all the battery cells in the battery cell package.Additionally, fire proofing material is utilized around the batterycells to absorb energy during a thermal runaway event, which is meant toprevent propagation of failure from battery cell to battery cell. Thebattery cell package must accommodate the combination of the liquidcooling system and the fire proofing material, resulting in a largerbattery cell package. However, liquid cooling systems typically requireextra space within the battery cell package for the coolant tubing andpiping, and can add manufacturing complexity.

Embodiments of the present invention are directed to systems that allowfor forced air cooling in larger battery cell packages, whilemaintaining single battery cell containment for prevention of propagatedthermal runaway from battery cell to battery cell in a battery cellpackage. The forced air cooling is provided by a fan located at thefront of the battery cell package, where air is drawn through an inleton the front surface of the battery cell package. The air is forcedtowards an air plenum assembly which includes a designated coolingplenum and exhaust plenum, where the forced air enters an inlet of thecooling plenum. The cooling plenum includes a plurality of apertures fordispersing the forced air into each battery compartment, where a singlebattery compartment includes a single battery cell. Additionally, eachbattery compartment includes thermal separators made of an electricallynon-conductive heat resistant and high melting point material to preventpropagated thermal runaway from battery cell to battery cell. Theinduced air pressure gradient in each of the battery compartments due tothe forced air entering each battery compartment allows for the heatedair to exhaust through a vent into the exhaust plenum. The heated airtravels through the exhaust plenum and out the rear of the battery cellpackage, where the rear surface of the battery cell package includes avent for exhausting the heated air. Advantages of the present inventionmay include a lower space requirement in the battery cell packages forthe plenum assembly as opposed to the coolant tubing and piping requiredfor a liquid cooled system, less manufacturing complexity, and lowermanufacturing cost.

Detailed embodiments of the present invention are disclosed herein withreference to the accompanying drawings; however, it is to be understoodthat the disclosed embodiments are merely illustrative of potentialembodiments of the invention and may take various forms. In addition,each of the examples given in connection with the various embodiments isalso intended to be illustrative, and not restrictive. This descriptionis intended to be interpreted merely as a representative basis forteaching one skilled in the art to variously employ the various aspectsof the present disclosure. In the description, details of well-knownfeatures and techniques may be omitted to avoid unnecessarily obscuringthe presented embodiments.

FIG. 1A depicts an air plenum assembly, in accordance with an embodimentof the present invention. In this embodiment, air plenum assembly 100includes cooling plenum 102, top exhausting plenum 104, and bottomexhausting plenum 106. Cooling plenum 102 enclosed by a conduit forcooling includes inlet 108, where cooled or ambient air is forcedthrough inlet 108 of cooling plenum 102. Air intake through inlet 108occurs at one end of cooling plenum 102 and cooling plenum 102 is sealedat the other end, opposite inlet 108. Top exhausting plenum 104 enclosedby a conduit for exhausting heated air includes top outlet 110 andbottom exhausting plenum 106 enclosed by a conduit for exhausting heatedair includes bottom outlet 112, where heated air is evacuated from eachof the battery cells and exhausted through top outlet 110 and bottomoutlet 112. In an alternative embodiment, air plenum assembly 100 caninclude cooling plenum 102 and top exhausting plenum 104 or coolingplenum 102 and bottom exhausting plenum 106. Additionally, air plenumassembly 100 can include multiple cooling plenums 102, to maximize anamount of cooled or ambient air directed towards the battery cells. Topexhausting plenum 104 is at least partially coupled to a top portion ofcooling plenum 102 and bottom exhausting plenum 106 is at leastpartially coupled to a bottom portion of cooling plenum 102.

Cooling plenum 102 includes a plurality of apertures 114 through whichcooled or ambient air forced through inlet 108 is directed into eachbattery compartment housing a battery cell. Top exhausting plenum 104includes a plurality of top vents 116 and bottom exhausting plenum 106includes a plurality of bottom vents 118. In addition to aperture 114,each compartment housing the battery cell includes top vent 116 andbottom vent 118 for evacuating heat from each of the battery cells. Ascooled or ambient air is forced through inlet 108, the air travelsthrough the length of cooling plenum 102 and a portion of the air isforced through each of the apertures 114. In this embodiment, coolingplenum 102 is a rectangular shaped conduit extending the full length ofair plenum assembly 100. In another embodiment, cooling plenum 102gradually tapers towards the far end of air plenum assembly 100 oppositeinlet 108, where a passage area for the cooled or ambient air forcethrough cooling plenum 102 is greatest near inlet 108. Tapering thepassage area for the cooled or ambient air through cooling plenum 102allows for an acceleration of the cooled or ambient airflow towards thefar end of cooling plenum. Additionally, the passage area can vary insize at different points along cooling plenum 102 to control thevelocity of the cooled or ambient air. In yet another embodiment, topexhausting plenum 104 and bottom exhausting plenum 106 can eachgradually taper towards the far end of air plenum assembly 100 oppositetop outlet 110 and bottom outlet 112, respectively, where a passage areafor the heated air through top exhausting plenum 104 and bottomexhausting plenum 106 is greatest near top outlet 110 and bottom outlet112, respectively. As described with regards to cooling plenum 102, thepassage area can vary in size at different points along top exhaustingplenum 104 and bottom exhausting plenum 106 to control the velocity ofthe exhausted heated air.

FIG. 1B depicts an enhanced view of a portion of the air plenum assemblyof FIG. 1A, in accordance with an embodiment of the present invention.In this embodiment, each of the plurality of top vents 116 and each ofthe plurality of bottom vents 118 have the same dimensions. A singlebattery cell is situated in a single battery compartment, where thesingle battery compartment includes a single aperture 114, top vent 116,and bottom vent 118. The single battery compartment is partiallyenclosed, where the only openings for the single battery compartment isaperture 114, top vent 116, and bottom vent 118. The dimensions, shape,and location of each of the plurality of top vents 116 and each of theplurality of bottom vents 118 can vary depending on exhaust requirementsfor each of the battery cells. In this embodiment, the dimensions andshape of top vents 116 and bottom vents 118 are such to maximize thepassage area for exhausting air from each of the single batterycompartments.

In this embodiment, each of the plurality of apertures 114 have the samedimensions. The dimensions, shape, and location of each of the pluralityof apertures 114 can vary depending on cooling requirements for each ofthe battery cells. For example, a cooling requirement can include alocation of aperture 114 for equally impinging the forced air ontobattery cell. Another cooling requirement can include a location ofaperture 114 for creating a maximum amount of induced air pressuregradient to evacuate heat at a greater rate through top vent 116 andbottom vent 118 out of the single battery compartment and away from thebattery cell. The single battery compartment is not limited to a singleaperture 114 and can include two or more apertures 114.

In this embodiment, center line 120A, 120B, 120C, and 120D representscenter lines to which thermal separators align with. A first thermalseparator aligns with center line 120A for a total height of air plenumassembly 100, which equals the sum of the height of cooling plenum 102,top exhausting plenum 104, and bottom exhausting plenum 106. A secondthermal separator aligns with center line 120B, where an area betweenthe first thermal separator and the second thermal separator representtwo walls of battery compartment 124 for a single battery cell.

FIG. 2 depicts an isometric view of a plurality of air plenum assembliesin a battery cell package, in accordance with one embodiment of thepresent invention. In this embodiment, battery cell package 200 includesenclosure 202, where a top portion of enclosure 202 is removable toexpose the internal components of battery cell package 200. Enclosure202 includes front portion 204 and rear portion 206, where front portion204 includes inlet aperture 208 for air intake by fan 210. Fan 210accelerates air towards air plenum assemblies 100 and printed circuitboard assemblies 212. In this embodiment, there are four air plenumassemblies 100 and four printed circuit board assemblies 212. Eachprinted circuit board assembly 212 includes a row of coupled thermalseparators 214 between each of the electrically coupled battery cells216. Circuit board assembly 212 can include one or more battery cells216 and two or more thermal separators 214, where each battery cell 216includes two thermal separators 214 on both sides of each battery cell216. Each printed circuit board assembly 212 also includes a designatedair plenum assembly 100 for cooling the row of battery cells 216electrically coupled to each printed circuit board assembly 212.

FIG. 3 depicts a top view of the plurality of air plenum assemblies inthe battery cell package of FIG. 2, in accordance with one embodiment ofthe present invention. In this embodiment, fan 210 located at frontportion 204 of battery cell package 200 is centered between the four airplenum assemblies and the four printed circuit board assemblies 212 toallow for the symmetrical air distribution. Each printed circuit boardassembly 212 is parallel to each respective air plenum assembly 100.Each battery cell 216 is encased lengthwise by air plenum assembly 100,printed circuit board assembly 212, and two thermal separators 214.Thermal separators 214 are made from an electrically non-conductive heatresistant, high strength, and high melting point material, relative toeach battery cell 216. The melting point temperature of thermalseparators 214 is greater than temperatures experienced by battery cell216 during a thermal runaway event to ensure each battery cell 216 iscontained in each batter compartment.

In this embodiment, a first thermal separator 214 is located oppositeand in parallel to a second thermal separator 214. Printed circuit boardassembly 212 is located perpendicular at one end of the two thermalseparators 214 and air plenum assembly 100 is located perpendicular atanother end of two thermal separators 214, opposite printed circuitboard assembly 212. Each battery cell 216 is encased widthwise by abottom cover and a top cover of battery cell package 200, where thebottom cover and the top cover is located perpendicular to the firstthermal separator 214 and the second thermal separator 214. The bottomcover of battery cell package 200 creates a first seal between the firstthermal separator 214 and the second thermal separator 214 and the topcover of battery cell package 200 creates a second seal between thefirst thermal separator 214 and the second thermal separator 214.

FIG. 4 depicts an enhanced top view of a single row of battery cellswith an air plenum assembly in the battery cell package of FIG. 2, inaccordance with one embodiment of the present invention. In thisembodiment, each battery cell 216 is orientated 180 degrees from anadjacent battery cell 216 that is electrically coupled to printedcircuit board assembly 212. Each battery cell 216 shares at least onethermal separator with a neighboring battery cell 216. As illustrated,air plenum assembly 100 includes inner conduit 402 through which heatedair is evacuated through an exhaust plenum. Walls 404 of exhaust plenumalign and couple with thermal separators 214 to encase each battery cell216, such that heated air is forced into inner conduit 402 of air plenumassembly 100 and evacuated through the exhaust plenum. In anotherembodiment, each wall 404 can extend beyond the width of each thermalseparator 214 to restrict the amount of heated air forced into innerconduit 402 of air plenum assembly 100. Thermal separators 214 and airplenum assembly 100 prevents air in one battery compartment fromentering another battery compartment, resulting in isolation forprevention of thermal runaway propagation from battery cell to batterycell.

FIG. 5 depicts a front inlet view of the plurality of air plenumassemblies in the battery cell package of FIG. 2, in accordance with oneembodiment of the present invention. In this embodiment, cooled orambient air is forced through each inlet 108 of each cooling plenum 102of air plenum assembly 100 at front portion 204 of battery cell package200. The cooled or ambient air forced through each inlet 108 dispersesinto each compartment housing battery cell 216 of each printed circuitboard assembly 212. Each of the four inlets 108 represent a directedpath through which the forced cooled or ambient air can take due tothermal separators 214, a bottom surface of battery cell package 200,and a top surface of battery cell package 200 (not illustrated in FIG.5) preventing the leaking of the forced cooled or ambient air into othersurrounding areas.

FIG. 6 depicts a rear outlet view of the plurality of air plenumassemblies in the battery cell package of FIG. 2, in accordance with oneembodiment of the present invention. In the embodiment, heated air isforced through top outlet 110 of top exhausting plenum 104 and bottomoutlet 112 of bottom exhausting plenum 106 towards rear portion 206 ofbattery cell package 200. As air is forced into air plenum assembly 100and dispersed into each compartment housing battery cell 216, the air isimpinged onto each battery cell 216. The heated air is exhausted out ofeach compartment housing battery cell 216 and through top exhaustingplenum 104 and bottom exhaust plenum 106. Each of the four top outlets110 and each of the four bottom outlets 112 exhaust the heated air outof rear portion 206 of battery cell package 200. Battery cell package200 includes a rear wall at rear portion 206 with venting outlets (notillustrated in FIG. 6), for exhausting the heated air out of batterycell package 200. Thermal separator 214 prevents backflow of heated airexhausted out of top outlet 110 and bottom outlet 112 from recirculatingback onto the final battery cell 216 of each printed circuit boardassembly 212.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting to the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

Having described preferred embodiments of a cooled containmentcompartment for package battery cells (which are intended to beillustrative and not limiting), it is noted that modifications andvariations may be made by persons skilled in the art in light of theabove teachings. It is therefore to be understood that changes may bemade in the particular embodiments disclosed which are within the scopeof the invention as outlined by the appended claims.

What is claimed is:
 1. An apparatus for cooling and containing packagedbattery cells, the apparatus comprising: a first plenum enclosed by afirst conduit for cooling, wherein the first plenum includes an inletfor air intake located at a first side of the first plenum; a secondplenum enclosed by a second conduit for exhausting heated air, whereinthe second plenum includes an outlet for exhausting air located at afirst side of the second plenum, wherein a second side of the firstplenum is at least partially coupled lengthwise to a second side of thesecond plenum; a first aperture located on a third side of the firstplenum for directing air from the inlet at the first side of the firstplenum into a first compartment, wherein the first compartment includesa first battery cell, wherein dimensions and shape of the first apertureare based on cooling requirements of the first compartment that include:a location of the first aperture on the third side of the first plenumfor creating an induced air pressure gradient to exhaust air away fromthe first battery cell in the first compartment; and a first ventlocated on a third side of the second plenum for exhausting air awayfrom the first compartment towards the outlet at the first side of thesecond plenum.
 2. The apparatus of claim 1, wherein the inlet at thefirst side of the first plenum is located opposite to the outlet at thefirst side of the second plenum.
 3. The apparatus of claim 2, whereinthe first compartment comprises: a first printed circuit board assemblyelectrically coupled to the first battery cell; a first thermalseparator coupled to the first printed circuit board assembly, whereinthe first thermal separator aligns with a first side of the first ventand the first printed circuit board aligns with a second side of thefirst vent; and a second thermal separator coupled to the first printedcircuit board assembly, wherein the second thermal separator aligns witha third side of the first vent.
 4. The apparatus of claim 3, wherein thefirst compartment further comprises: a first side of an enclosurelocated perpendicular to a first side of the first thermal separator anda first side of the second thermal separator, wherein the first of thefirst thermal separator and the first side of the second thermalseparator create a first seal with the first side of the enclosure; anda second side of the enclosure located perpendicular to a second side ofthe first thermal separator and a second side of the second thermalseparator, wherein the second of the first thermal separator and thesecond side of the second thermal separator create a second seal withthe second side of the enclosure.
 5. The apparatus of claim 4, whereinthe first compartment is formed by the first printed circuit boardassembly, the first thermal separator, the second thermal separator, thefirst side of the enclosure, the second side of the enclosure, the firstside of the first plenum, and the first side of the second plenum. 6.The apparatus of claim 5, wherein the cooling requirements include alocation of the first aperture on the third side of the first plenum forimpinging air onto the first battery cell located in the firstcompartment.
 7. The apparatus of claim 1, wherein dimension and shape ofthe first vent are based on exhaust requirements for the firstcompartment.
 8. The apparatus of claim 1, wherein each of the firstthermal separator and the second thermal separator is an electricallynon-conductive heat resistant material and of a higher melting pointrelative to the first battery cell.
 9. The apparatus of claim 1, furthercomprising: a third side of the enclosure, wherein the third side of theenclosure includes an inlet for directing air towards a fan located inthe enclosure, wherein the third side is located adjacent to the inletat the first side of the first plenum; and a fourth side of theenclosure, wherein the four side of the enclosure is located oppositethe third side of the enclosure, wherein the fourth side of theenclosure is located adjacent to the outlet at the first side of thesecond plenum.
 10. The apparatus of claim 2, further comprising: a thirdplenum enclosed by a third conduit for exhaust heated air, wherein thethird plenum includes an outlet for exhausting air located at a firstside of the third plenum; and a first vent located on a first side ofthe third plenum for exhausting air away from the first compartmenttowards the outlet at the first side of the third plenum.
 11. Theapparatus of claim 10, wherein the outlet at the first side of the thirdplenum aligns with the outlet at the first side of the second plenum.12. The apparatus of claim 10, wherein the third plenum is at leastpartially coupled lengthwise to the first plenum, opposite the secondplenum.
 13. The apparatus of claim 3, further comprising: a secondaperture located on the third side of the first plenum for directing airfrom the inlet at the first side of the first plenum to a secondcompartment, wherein the second aperture is adjacent to the firstaperture; and a second vent located on the third side of the secondplenum for exhausting air away from the second compartment towards theoutlet at the first side of the second plenum, wherein the second ventis adjacent to the first vent.
 14. The apparatus of claim 13, whereinthe second compartment comprises: a second battery cell electricallycoupled to the first printed circuit board assembly; and a third thermalseparator coupled to the first printed circuit board assembly, whereinthe third thermal separator aligns with a first side of the second vent.15. The apparatus of claim 13, wherein the first compartment includes afirst side of the second thermal separator and the second compartmentincludes a second side of the second thermal separator.
 16. Theapparatus of claim 1, wherein the first plenum tapers towards a fourthside of the first plenum opposite the first side of the first plenum.17. The apparatus of claim 1, wherein the second plenum tapers towards afourth side of the second plenum opposite the first side the secondplenum.
 18. The apparatus of claim 10, wherein the third plenum taperstowards a fourth side of the third plenum opposite the first side of thethird plenum.